The present invention relates to an imaging module for biometrics authentication, a biometrics authentication apparatus and a prism, and in particular, to an imaging module, etc. for biometrics authentication that are suitable for miniaturization and low-profiling.
In recent years, further miniaturization and low-profiling are commonly requested in applications area of personal devices such as cellular phones, PCs (Personal Computers) and PDAs (Personal Digital Assistants).
Meanwhile, in the field of such personal devices, security measures against unauthorized use of a device when the device is lost, stolen, etc. are greatly desired in these years. As one of the security measures, a technology applying biometrics authentication (using finger vein patterns, for example) to personal devices is being highly expected. The authentication using finger vein patterns is effective as biometrics authentication since the finger vein pattern differs from individual to individual. The finger vein authentication technology is especially advantageous in that the technology, which is generally not associated by people with criminal investigations differently from fingerprint authentication, does not cause psychological resistance and in that counterfeiting a finger vein pattern, not as information on the surface of a living body (which can be easily observed from outside) but as characteristics inside a living body, is difficult.
The finger vein authentication is performed by use of near-infrared rays, for example, since near-infrared rays are absorbed by hemoglobins contained in human blood while substantially penetrating other parts of a living body. In an image that is obtained by irradiating a finger (targeted part) of a person with near-infrared rays from outside and detecting light emerging from the finger (living body), muscular tissues and bones in the living body are described as white or bright parts, while blood vessels absorbing near-infrared rays are described as black or dark parts. A vein pattern is acquired based on the difference in the brightness, and the authentication of the person (personal authentication) is carried out by comparing the acquired vein pattern with vein patterns that have been registered previously.
In order to implement the vein authentication function in personal devices such as notebook PCs, an imaging module further miniaturized and low-profiled than conventional imaging modules is being desired to be developed.
Under such circumstances, a technique employed in JP-A-2006-198174 has been widely known as a technique for miniaturizing an imaging module for finger authentication.
The technique disclosed in JP-A-2006-198174 acquires information on a living body (a finger of a person) by irradiating lateral parts of the finger with near-infrared rays, deflecting the near-infrared rays emerging from the finger after traveling (being reflected and dispersed) inside the finger with a reflecting mirror, converting the deflected rays into an electric signal with a CCD (Charge-Coupled Device) sensor, and converting the electric signal into two-dimensional image data with an authentication unit.